Burnside Bridge traversing Antietam Creek near Sharpsburg, Maryland, site of heavy combat during the Battle of Antietam (Sharpsburg) on September 17, 1862
The middle bridge over Antietam Creek, also near Sharpsburg, photographed September 1862
The watershed area is 93 square miles (241 km²) and includes parts of Franklin County, Pennsylvania and Washington County, Maryland. Major tributaries in Pennsylvania include the East Branch of Antietam Creek, the West Branch of Antietam Creek, Red Run and Falls Creek. Major tributaries in Maryland include Little Antietam Creek, Beaver Creek, and Marsh Run.
The creek is noted for numerous well preserved stone arch bridges dating to the 19th Century that still traverse the creek, the most famous of which is the 125 foot (38 meter) long Burnside's Bridge in the Antietam National Battlefield.
Most of the watershed area is relatively rural in nature but the area surrounding Hagerstown, Maryland, is threatened by urban sprawl. The area is also heavily cultivated and waste runoff from farms is a growing ecological concern.
The creek was a major topographic feature during the Battle of Antietam (called the Battle of Sharpsburg in the American South) fought on September 17, 1862, near Sharpsburg, Maryland. Burnside Bridge, which traverses the creek, became a major focus of combat as Union forces under General Ambrose Burnside repeatedly tried to capture the bridge from Confederate forces guarding the crossing from a high bluff overlooking the creek. The day of the battle is known as "the day Antietam Creek ran red" due to the blood of thousands of Union casualties mixing with the creek waters.
